Work-supporting rest for turning-tools.



J. HARTNESS. WORK SUPPORTING BEST FOR TURNING TOOLS.

APPLICATION FILED OUT. 17, 1906.

Patented Feb. 28, 1911.

JAMES HARTNESS,

OF SPRINGFIELD, VERMONT.

WORK-SUPPORTING BEST FOR TURNING-TOOLS.

Specification of Letters Patent.

Patented Feb. 28, 1.911.

Original application filed November 24, 1905, Serial No. 288,970.Divided and this application filed October 17, 1906. Serial No. 339,349.

To all whom it may concern:

Be lli'kllOWIl that I, JAMES HAn'rNnss, of

Springfield, in the county of lVindsor and.

State of Vermont, have invented certain new and useful Improvements inVVork- Supporting Rests for Turning-Tools, of which the following is aspecification.

This invention has relation generally to turning tools for lathes andmore particularly to devices for supporting the work in the operation ofturning to prevent the work from springing under the thrust of thecutter.

It has been proposed heretofore to em ploy rolls as back and top rests,and except for certain disadvantages they are highly satisfactoryinasmuch as they reduce the friction which. operates to limit the speedof the work being turned. Nevertheless, in the employment of such rolls,there is always a tendency for the work to carry chips and grit betweenit and the rolls so as to spring the work toward the cutter with theresult that the work is not perfectly and evenly turned. Again the rollsare apt to become uneven, eccentric or imperfect in shape so that thework itself will be effected by such variation. Thus on account of theuncertain operation of the roller back and top rests, it has beennecessary to use the ordinary flat rests to obtain accurate results. Theobjection to the use of a single contact flat rest however is that it issoon destroyed by the friction of the work running at the high speedthat obtains in modern machine shop practice. This makes it necessary toeither reduce the size of the chip or the speed of the work, or in someway relieve the pressure at the point of contact.

The object of the present invention is to provide work rests having noneof the disadvantages of the single contact rests or the roller rests sothat the work may be driven at high speed without causing thedestruction of the work-engaging surfaces of the rests.

The present invention, therefore, contemplates the employment of doublecontact surfaces for both the top and the back rests; that is to say, Ipreferably employ a top rest and a back rest, each of which is notchedto provide adjacent surfaces with which the work may make contact. Inorder to insure an equal contact of the work with both of the surfaceson each rest, the rest itself is mounted pivotally. Thus each rest iscapable of rotation about its pivot and yet is in sliding contact withthe work. This makes it possible to rotate the work to a speed as highthe present steels will stand without resorting to rotating rollerrests.

Referring to the accompanying drawings, which illustrate one embodimentof the in- \-'ention,Figure 1 represents a turning tool, the mainfeatures of which are illustrated, described and claimed in LettersPatent No. 860,802, granted July 28, 1907, from which this applicationwas divided. Fig. 2 represents a section on the line 2-2 of Fig. 1..Fig. 3 represents in perspective view oneof the rest carriers with aswiveled rest em bodying the invention supported thereby. Fig. atrepresents an end view of the same. Fig. 5 represents a convenient formof the rest.

As set forth in said Letters Patent, hereinbefore referred to, the toolis provided with a cutter 10, adjustably supported on a cutter carrier11, pivoted or fulcrumed at 12. The work rests are indicated at 13 13.Each may be mounted upon a carrier consisting of a relatively short arm14 having a transverse cylindrical aperture, the walls of which arehardened to receive a hardened cylindrical crank pin 15. The arm at itsother end is provided with oppositely projecting trunnions 16 16, whichconstitute a rock or crank shaft and which are fitted in an open socketor hearing 17. One of the trunnions extends out as far as the end of thehardened crank pin 15 and is formed with the groove 18 to receive thework rest as illustrated in Fig. 3. As described in said Letters Patent,a plurality of abutments are provided for each work rest so that theymay be maintained in any desired position according to the diameter ofthe work. These abutments are indicated at 19 20. Each work restconsists of a disk or plate which is centrally aper tured to receive oneof the pins 15 and it is held against movement in the direction of itsaxis by the walls of the groove 18 in one of the trunnions 16. The diskis provided with one or more transverse peripheral notches as at a a a(see Fig. 1). notches will preferably be V-shaped or in the form ofreentrant angles, to provide surfaces to be engaged by the work, thoughI should not regard it as a departure from the invention if the notcheswere rounded These 1 or in the form of arcs of circles of differentdiameters, as lllustrated in Fig. 5.

By the employment of swivels as back rests, it will be observed thateach back rest will automatically accommodate itself to the work, andthat it may be partially rotated so as to bring a difierent notch intooperative position with relation to the work. Assuming, for example,that the thrust against each of the rests 13 in Fig. l is approximately1,000 pounds, it will be under stood that it is divided between twocontact points, thus making the running contact with each surface of therest only 500 pounds. Each rest equalizes its contact with the workautomatically, and, as previously stated, permits the work to be run toa maximum speed. The rest, which is directly opposite the cutter, isgenerally termed the back rest and the rest which is located in positionto resist the lateral thrust of the work may be termed the top rest Idesire to have it understood that the phraseology which I have employedis for the purpose of description and not of limitation, and that theinvention may be embodied in other forms which may readily suggestthemselves to those skilled in the art to which this invention relates.

While I preferably form both of the rests, which may be termed notchesor forked rests, with pivot apertures, around which they may move toaccommodate themselves to the work, nevertheless should occasion arise,I might replace either of them with a roller rest substantially asdescribed in my said Letters Patent No. 860,802.

Having thus explained the nature of my invention and described a way ofconstructing and using the same, although without attempting to setforth all of the forms in which it may be made, or all of the modes ofits use, I declare that what I claim is 1. A turning tool comprising acutter, a

equalize the pressure of said bearing surfaces on the work.

2. A turning tool comprising a cutter, and a work rest comprising apivot and a rest loosely movable about the axis of the pivot and havinga transverse peripheral notch, said rest and pivot being arranged withrelation to the cutter, and the rest being freely movable about saidpivot, so that the walls of the notch accommodate themselves to the workand resist the lateral thrust thereof due to the action of the cutter onthe work.

3. A turning tool comprising a cutter, a top rest, and a back rest, oneof said rests being notched to provide a double bearing surface on thework and a pivot on which said last-mentioned rest is loosely pivotedand about which it is free to move, whereby it may yield about its pivotto equalize the pressure on each wall ofthe notch and hold the workagainst the thrust of the cutter thereon.

4. In combination with the support therefor, of a pivot projecting fromsaid support, and a work rest free to rotate about said pivot when inoperative relation to the work, and having a peripheral notch extendinglongitudinally of said pivot to receive said work, substantially as setforth.

In testimony whereof I have aflixed my signature, in presence of twowitnesses.

JAMES HARTNESS.

\Vitnesses A. N. HOWE, A. S. MUNRo.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Yatents, Washington, I). C.

